City defenders Rory McArdle and Stephen Darby are likely to miss the start of the new 2016/2017 campaign due to long-standing injuries.
McArdle underwent an operation on Wednesday to help stabilise the front of his left shoulder.
The centre half suffered a dislocation in the area towards the end of the away game at Bury back in March, leading to a period of five weeks on the sidelines, but he was able to finish the season off by wearing shoulder protection.
Darby has begun a series of injections to try and finally cure a groin problem that had been troubling the City skipper throughout the whole of last season.
City Head Physio Matt Barrass said: "It has got to the point with both of them that for the sake of missing the first few weeks of the season, hopefully we can get these issues finally sorted out.
"We are advised with Rory that it will be four months after the operation before he can do any full-contact training, hopefully we might be able to get it down to three (months) though.
"Stephen, in theory, has a better chance of making the start of the season but it just depends on how much fitness work we can get in him."